To make contact; to cover all the possibilities. Comes from baseball where the runners need to touch the base to make a run legal. Mostly used by asshat salesmen and contractors when they want to talk to you over the phone to see if you're interested in something they have for sale, usually around dinner time.

"I'm just calling to Touch Base to see if you need our crappy product/service."
"No, fuck. Leave me alone."

The Urban Dictionary T-Shirt

To make contact; to cover all the possibilities. Comes from baseball where the runners need to touch the base to make a run legal. Mostly used by asshat supervisors who do no real work, but constantly engage in meta-communication.

Boss: "I'm just calling you to make sure we touch base."
Worker: "Alright, what do we need to discuss?"
Boss: "Well the first thing we need to do is touch base."
Worker: "So the point of this call is to have a call?"
Boss: "Exactly. That's why touching base is so important."
Worker: *muttered* "Go to hell, you recursive asshat."

The Urban Dictionary T-Shirt

Most appropriately a business expression originating approximately 40-years-ago derived from the sport of baseball. During that time it was a novel and well accepted slang for the purpose of getting-in-touch with someone over any form of matter. By 1990, it became so over used to the point of becoming a corny expression eventually leading to the use mostly by an asshat as described. Today, such an expression is regarded practically as an insult for this very reason and is taken as a form of senseless needling, often meant to offend one's intelligence.

The only businesses who have become notorious for the term are financial institutions where, in fact, new employees are actually taught to use it in the form of customer psychology as it belittles the status of the borrower in relation to the lender, e.g., reminding the customer who the lender is and that they are in debt.

"Hi, John, this is Lois at Bullshit Finance! Just wanted to touch base and see how you are?"